implemented FastMatcher

.gitignore

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+/node_modules/

fastMatcher.js

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+function FastMatcher(list, options) {
+  this.list     = list;
+  this.options  = options || {};
+  this.matches  = this.options.matches || [];
+
+  var selector = this.selector = this.createSelector();
+  this.list.sort(function(x, y) {
+    return compare(selector(x), selector(y));
+  });
+}
+
+/**
+ * @example
+ * function createSelector(property) {
+ *   return new FastMatcher([], { selector: property }).createSelector();
+ * }
+ *
+ * createSelector()('foo'); // => 'foo'
+ * createSelector('x')({ x: 'bar'}); // => 'bar'
+ */
+FastMatcher.prototype.createSelector = function createSelector() {
+  var selector = this.options.selector;
+  if (selector) {
+    return function(x) { return x[selector]; };
+  }
+
+  return function(x) { return x; };
+};
+
+/**
+ * @example
+ * var fm = new FastMatcher(['ab', 'ac', 'ba', 'bc']);
+ *
+ * fm.getMatches('a'); // => ['ab', 'ac']
+ */
+FastMatcher.prototype.getMatches = function getMatches(prefix) {
+  var limit    = this.options.limit || 25,
+      selector = this.selector;
+
+  var list    = this.list,
+      matches = this.matches,
+      index   = this.findIndex(prefix);
+
+  matches.length = 0;
+  while (index < list.length && matches.length < limit && startsWith(selector(list[index]), prefix)) {
+    matches.push(list[index++]);
+  }
+
+  return matches;
+};
+
+FastMatcher.prototype.findIndex = function findIndex(prefix) {
+  var list     = this.list,
+      selector = this.selector,
+      lower    = 0,
+      upper    = list.length,
+      i;
+
+  while (lower < upper) {
+    i = (lower + upper) >>> 1;
+    if (compare(selector(list[i]), prefix) === -1) {
+      lower = i + 1;
+    } else {
+      upper = i;
+    }
+  }
+  return lower;
+};
+
+/**
+ * @private
+ * @example
+ * compare('foo', 'foo'); // => 0
+ * compare('foo', 'bar'); // => 1
+ * compare('bar', 'foo'); // => -1
+ */
+function compare(x, y) {
+  if (x == y) { return 0; }
+  return x > y ? 1 : -1;
+}
+
+/**
+ * @private
+ * @example
+ * startsWith('foo', 'f');  // => true
+ * startsWith('bar', 'f');  // => false
+ * startsWith('foo', 'fo'); // => true
+ * startsWith('foo', 'o');  // => false
+ */
+function startsWith(string, prefix) {
+  return string.lastIndexOf(prefix, prefix.length) === 0;
+}
+
+if (typeof module === 'object' && (module && module.exports)) {
+  module.exports = FastMatcher;
+}

package.json

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+{
+  "name": "fast-matcher",
+  "version": "0.1.0",
+  "description": "Find matches fast",
+  "main": "fastMatcher.js",
+  "scripts": {
+    "test": "autodoc -t fastMatcher.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/dtao/fast-matcher"
+  },
+  "author": "Dan Tao <[email protected]>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/dtao/fast-matcher/issues"
+  },
+  "devDependencies": {
+    "autodoc": "~0.6.1"
+  }
+}